Functionalized Dendritic Oligothiophenes: Ruthenium Phthalocyanine Complexes and Their Application in Bulk Heterojunction Solar Cells

Within the present work, two series of novel ruthenium(II) phthalocyanine (RuPc) complexes with one [RuPcCOPy-nT] or two [RuPc(Py-nT)(2)] dendritic oligothiophene (DOT) ligands in the axial positions are reported. The ability of Ru-II for axial coordination in RuPcs allowed the attachment of the PC through the metal site to the DOT-ligands bearing pyridine at the core position of the dendrons. These extended pyridine functionalized conjugated DOT-ligands (Py-nT) were chosen to cover the spectral window between 380 and 550 nm, where the RuPc does not exhibit a strong absorption, in order to improve the light-absorption of these complexes and hence enhance the efficiency of the corresponding solar cells. Good efficiencies of up to 1.6% have been achieved when blended together with a fullerene acceptor in solution-processed photovoltaic devices, providing by far the best phthalocyanine-based bulk heterojunction solar cells reported to-date.